*4.8. Transparency and Color Analysis*

The light transmission of the prepared films was quantified at 550 nm wavelength using an ONDA-Vis spectrophotometer, V-10 Plus, ONDA, Padova, Italy. Film strips were placed in a spectrophotometer test cell, and the transparency of the films was determined as per the methodology described by Zhao et al. [34].

A Konica Minolta colorimeter (Konica Minolta, Tokyo, Japan) was utilized to perform color analysis of the film samples. The *L*\*, *a*\*, and *b*\* parameters were measured on a reference plate with a lightness value of 100. The analysis was conducted at different points on the surface of the films. The equation utilized for the computation of the overall color variation is as follows:

$$
\Delta E^\* = \left[ (\Delta L^\*)^2 + (\Delta a^\*)^2 + (\Delta b^\*)^2 \right]^{1/2} \tag{5}
$$

*L*: lightness, *a*\*: green-red color, *b*\*: blue-yellow color, and ∆*E*\*: overall color variation.
